The present invention relates to a magnetic head for performing recording such as magneto-optical recording by applying a modulation magnetic field while increasing the temperature of a recording site, and also to a magnetic head assembly using such a magnetic head, and in particular, to a configuration of its magnetic pole.
FIG. 8 is a perspective view showing a structure of a typical conventional magnetic head 1. The magnetic head 1 is a magnetic head for use in mini-disc (xe2x80x9cMDxe2x80x9d hereinafter) devices which employ magneto-optical recording. The magnetic head 1 has a structure, wherein, schematically, a coil 4 is wound around a central magnetic pole 3 of a E-shape core 2. The E-shape core 2 has an integral structure composed of the central magnetic pole 3 in the form of a pillar and a yolk portion 5 for enhancing the strength of a generated magnetic field, which are made of a magnetic material such as Mnxe2x80x94Zn ferrite. The coil 4 is made of an insulating material, and is fastened on the E-shape core 2 by being wound around a bobbin (not shown), which is then fitted to the central magnetic pole 3.
FIG. 9 shows a magnetic head assembly 11 employing the foregoing magnetic head 1, as viewed from the recording medium side. The magnetic head 1 is fastened on a slider 12 made of a slidable material. The slider 12 has a sliding part 13 which slides on the recording medium and holds the magnetic head 1 alone or in pair (in pair in FIG. 9) in a direction orthogonal to a sliding direction with respect to the recording medium, and is fastened on one end of a suspension 15 (mentioned later) by a link portion 14.
The sliding part 13 is formed by molding, for example, a polymer material such as polyarylate, nylon, and polyester, or a material having a low friction coefficient such as ceramic. Alternatively, the sliding part 13 may be made of other materials, and a material having a low friction coefficient in the form of a tape may be stuck to a portion which comes into contact with the recording medium.
The magnetic head 1 and the slider 12 are slidable in response to deflection of the recording medium, or dusts or protrusions, etc., on the recording medium. Thus, the magnetic head 1 and the slider 12 are normally supported under a pre-load of 3 mN to 10 mN by the suspension 15 which is made of a thin metal having a thickness in a range of 30 xcexcm to 100 xcexcm. The other end of the suspension 15 is supported by a fixing section.
In addition to the magnetic head 1, the slider 12, and the suspension 15, there is provided an upper regulating plate (not shown) to make up the magnetic head assembly 11. The upper regulating plate is provided to prevent any damage to the magnetic head 1, which may be caused by a collision between the magnetic head 1 and the outer casing due to vibrations, etc., on the entire device, or between the magnetic head 1 and the recording medium due to reaction to such vibrations.
FIG. 10 and FIG. 11 are a plan view and a cross sectional view, respectively, explaining how recording is carried out. A recording medium 21 is encased in a cartridge 22 for protection against damage or dusts, etc. The cartridge 22 has openings 23 and 24 of a near-rectangular shape respectively on the upper and lower sides thereof. The openings 23 and 24 are closed by a shutter (not shown) when the cartridge 22 is outside of the device.
When recording, a front end of the magnetic head assembly 11 moves into the cartridge 22 from the opening 23, and the sliding part 13 of the slider 12 comes into contact with the recording medium 21. As mentioned above, MDs employ magnetic modulation recording, and thus there is provided a light pick-up 25 directed to the recording medium 21 through the opening 24, on the opposite side of the magnetic head 1 with the magnetic medium 21 in between. The light pick-up 25 is displaceable in a radial direction of the recording medium 21 in an interlocked manner with the magnetic head 1. A portion irradiated with a laser beam from the light pick-up 25 becomes a recording site. Signals are recorded only on the recording site by the modulation magnetic field applied in the vicinity of the recording site by the magnetic head 1.
The described structure is called a sliding magnetic head and has currently been used commonly in MD devices. Meanwhile, in recent years, the MD devices have been marketed as applied to other applications such as digital still cameras, and further the MD devices are beginning to be used to record music data which have been distributed via networks. In these applications, by increasing the frequency of the modulation signal through the coil 4, the picture interval can be shortened and the image quality can be improved in digital still cameras, and the time of receiving music data can be reduced. Thus, there has been demand for increasing the currently used frequency of, for example, 720 kHz to the frequency of 10 MHz or greater.
However, when the frequency of the current through the coil 4 is increased, a core loss (hysteresis loss, overcurrent loss, etc.) by the core 2 increases abruptly, which results in significant increase in calorific value of the core 2. Further, when the temperature of the core 2 itself is increased, there were cases where the magnetic head 1 and the peripheral circuits were damaged as the temperature exceeded past the Curie point of the core material.
It is an object of the present invention to provide a magnetic head which can adapt to high frequencies while using the entire recording area of the recording medium, and a magnetic head assembly using the same.
In order to achieve this object, a magnetic head in accordance with the present invention is for applying a magnetic field for recording and erasing information to a temperature-increased recording site of a recording medium, and includes: a magnetic pole in the form of a pillar; a coil which is wound around the magnetic pole; and a magnetic body in the form of a flat plate to which one end of the magnetic pole is fastened, the magnetic body being formed asymmetrical about a relative displacement direction of the recording medium with respect to a portion where the magnetic pole is fastened.
According to this arrangement, the magnetic head is adapted to high frequencies by the provision of a core of a raised type composed of the magnetic pole being provided to rise on the magnetic body in the form of a flat plate, which provides a heat capacity which is required for the core and a heat radiation area which is required for the magnetic body, wherein the magnetic body is formed asymmetrical about a relative displacement direction of the recording medium.
Thus, by determining the shape of the magnetic body in accordance with the cartridge which encases the recording medium, or the mechanical components in the vicinity of the magnetic head, there will be no interference between the magnetic head and the cartridge or the mechanical components, even when the size of the magnetic core is increased due to the magnetic core of the raised shape. As a result, less restriction is imposed on the moving range of the magnetic head, thus making it possible to use the entire recording area of the recording medium.
Meanwhile, the heat capacity and the heat radiation area required for the core are provided by the magnetic body in the form of a flat plate, and therefore there will be no problem due to heat capacity and heat radiation area, thereby adapting to high frequencies.
For a fuller understanding of the nature and advantages of the invention, reference should be made to the ensuing detailed description taken in conjunction with the accompanying drawings.